Stuck? 
support@mecway.com
support@mecway.com
Mecway
FEA
Victor
About
- Username
- Victor
- Joined
- Visits
- 4,724
- Last Active
- Roles
- Administrator
Comments
-
I don't know much about soil and can't help there, sorry. It sounds like a more general engineering problem that perhaps you could ask on eng-tips.com
-
The most complete way is to use contact with nonlinear static 3D analysis and CCX and model the soil too. But if the whole surface remains held by static friction and doesn't separate from the soil, you can just use fixed support and look at the sh…
-
You're right that the failure criteria won't help - they are only for calculating factors of safety. The internal solver doesn't do progressive failure for composites. The CCX solver looks like it can if you define the brittle material using a pla…
-
A useful new option in 2.15 is *CONTROLS,PARAMETERS=CONTACT which allows you to increase the maximum number of iterations before it gives up. I just used that to get a difficult contact problem to solve which looked like it was converging but wouldn…
-
There appears to be one on this page: http://www.dhondt.de/ It's the last item in the CCX download list, confusingly called "files". Direct link http://www.dhondt.de/calculix_2.15_4win.zip
-
You could make it double thickness by extruding from both sides of each surface as shown in the attached picture. The corner nodes will end up a bit out of place so you'd have to reposition them manually. It should work pretty well using shells tho…
-
Yes. Tools -> Options -> Default model. You can also use File -> Import to add a model containing only a material to the currently open model.
-
You could try to use an actual solid mesh made from tet10 elements. You might need more than one element in the thickness direction for good accuracy but since it's fairly simple, you might get by without having too many elements. Sometimes you can…
-
All IGES files have this problem with Mecway. Please use STEP instead. IGES support is only really there for very old CAD software that somehow doesn't export STEP. I might remove that in future versions.
-
Thanks for this suggestion Steve. I'm trying to work out a cohesive way to include rigid body type features for bonding a beam to a whole surface, pivoting joints between solid mesh parts, and possibly fastener spiders. So loads and constraints dist…
-
You know, I'm not sure. It might simply be a lack of tests. They seem to work if you switch to Static 3D to set them up then back to modal vibration to solve. I'll look into enabling them properly.
-
Thanks for the suggestion Eduart. What I'm thinking about for that problem is named folders which you can use to group items into. Would that work just as well for you?
-
CCX has some error estimates. See the CCX manual for details. I don't know much about them though. There's a rule of thumb to not have the stress change by more than 10% of the whole range over a single element, which means no more than two colors …
-
You can define a nonlinear stress-strain curve by entering the CCX cards under CCX -> custom model definition. There's an example of that in the manual section 14.1 Custom model definition. I don't know about nonlinear Poisson's ratio. There are…
-
It's not just the reference values, but some of your results don't seem to be converging at all, such as σ_eq,s and σ_sθ which decrease with refinement until local refinement where they suddenly jump up to near the values from the coarsest mesh. Are…
-
I'm comparing to the finest solid mesh. I don't trust the theoretical values to use as a reference because the formulas seem too simple - No Poisson's ratio? Is stress inside or outside? Linear or nonlinear? Where do the k factors come from? Where d…
-
I'm still not seeing much problem. Where are you measuring the stresses? I checked some of them a small distance from the base, and von Mises is 0.5% error with 10,000 nodes. Axial is worse, but approximately 0 error for 39,000 nodes. Shear is the w…
-
I don't really see much of an accuracy problem. I tried to recreate the model from your PDF - 6.015 m diameter and 5 mm wall thickness, clamped at the base. I didn't get anywhere near the same stress so I probably have some parameter wrong, but I di…
-
You could try S8R instead of S8. I think that might perform better but I'm not sure about thin-walled structures in particular. It's now under CCX -> custom element type. The stress near the clamp presumably won't be correctly predicted by the t…
-
Yes, those are limitations of it, unfortunately. It's quite a low-level tool that's not good for local refinement and the R,S,T directions depend on the element's node connectivity which aren't necessarily related to the U,V,W element orientation co…
-
The procedure is similar to coupling thermal to mechanical for thermal stress. 1. Solve with DC current flow. 2. Add power density to the solution. 3. Switch to a Thermal analysis type and use Transfer internal heat generation from solution under Lo…
-
Either solver would do for the thermal solve. Then yes, switch to Static 3D or any mechanical analysis type that allows thermal stress. That will have to be CCX though. Define the temperature dependent Young's modulus using CCX cards.
-
While I don't know about RISA 3D specifically, there are a lot of formats Mecway can import nodes from. Here are the ones that other FEA software might be able to export: * .dxf POINTs become nodes. What settings are you concerned about? Just try…
-
Thank for working out those shear components. I checked all 6 of them on an arbitrary shaped model with an arbitrary stress state by: * comparing to stress in global coordinates in the XZ plane, and they're all the same as that on at least a coup…
-
You mean a way to make existing formulas available to other files? I'll try to make them work with Import but for now, you can open the .liml file with a text editor and copy and paste them between files. A formula looks like: m sqrt…
-
Do you mean that it imports with File -> Import? Or that it can be used for the loads and constraints too? In the first case, probably. I think it's just my oversight that it doesn't get imported. In the second case. It seems more complicated. …
-
It seems to fit more than about 60 000 characters. I don't know if it has a hard limit. It automatically wraps if the line is too long for the window.
-
The only other way I can think of is *PRE-TENSION SECTION. See the CCX manual for details. It's fairly complicated to set up but it couples two nodes together and to a reference node such that if you apply a force do the reference node, it becomes t…
-
Radial displacement is (x*u.x + y*u.y) / sqrt(x^2+y^2) which is the dot product of the normalized position vector and displacement. I think you can get tangential displacement with a cross product but not sure of the formula off the top of my head.…
-
I don't know how but I've heard of people solving much larger models. Perhaps check on the CalculiX Yahoo! group.
